On Jan 8, 2010, at 11:00 AM, Marc.Boudreau wrote:
No, the problem is that code can be run on a variety of database
platforms
like DB2, SQL Server, Oracle, etc...
So if I use @Column(columnDefinition="NVARCHAR(256)"), it will only
work on
SQL Server and Sybase, because the other database platforms don't
recognize
the NVARCHAR type.
I see. How about having the DataDictionary process the
columnDefinition in a database-specific way? IIRC, all of the
databases support national use character set columns but in their own
way.
The columnDefinition is not further standardized in the specification
so we can do anything we want to with it.
We could analyze the columnDefinition and look for the ANSI standard
strings NCHAR(n) and NVARCHAR(n) and translate these into the database-
specific type.
Craig
Craig L Russell wrote:
Hi,
On Jan 8, 2010, at 7:53 AM, Marc Boudreau wrote:
Currently, OpenJPA maps String fields to VARCHAR on SQLServer and
Sybase.
There doesn't appear to be a way to cause a String field to be
mapped to
NVARCHAR other than by using the @Column annotation and settings its
columnDefinition to "NVARCHAR".
What is the objection to using this technique on the columns that you
want to hold national use characters? It seems this use case is
exactly suited to this feature.
At the same time, blindly using NVARCHAR
for all String fields is too costly in terms of storage space on the
database. It ends up limiting the maximum size of the column (less
characters can fit because more bytes are used to store them).
Unfortunately, the applications we write are required to be database
neutral because we support multiple vendors.
I'd like to start a discussion on this matter. Here are a couple of
points
to lead us off...
What's the severity of this missing functionality?
Could an OpenJPA specific annotation be introduced to allow the
mapping
tool to use NVARCHAR instead of VARCHAR?.
Is the problem that the OpenJPA mapping tool doesn't support the
standard columnDefinition annotation in the way you want it to?
Craig
Marc Boudreau
Software Developer
IBM Cognos Content Manager
[email protected]
Phone: 613-356-6412
Craig L Russell
Architect, Sun Java Enterprise System http://db.apache.org/jdo
408 276-5638 mailto:[email protected]
P.S. A good JDO? O, Gasp!
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Craig L Russell
Architect, Sun Java Enterprise System http://db.apache.org/jdo
408 276-5638 mailto:[email protected]
P.S. A good JDO? O, Gasp!
